The invention is based on a priority application EP 05290613.8 which is hereby incorporated by reference.
The invention relates to a method for exchanging packets of user data between a terminal of a first network and a service provider of a second network.
For exchanging data between a service provider and a terminal, it is mandatory that both can establish a means by which to identify each other in ongoing communications. In the case that the service provider is an Internet service provider, e.g. of a DSL or other broadband network being deployed for high speed Internet services, and the terminal is a subscriber terminal of a home LAN, such a means is usually provided by the Internet service provider attributing an unique IP address to the terminal. In doing this, the Internet provider follows an approach for IP address allocation which assures that the same IP address cannot be attributed to more than one subscriber terminal.
If a second or subsequent service, e.g. a video service from a video service provider, is going to be offered, it is desirable that the IP address allocation strategy for the new service does not interfere with the existing IP address allocation strategy of the Internet service provider. Hence, it has to be ensured that when the Internet subscriber connects a set top box to their home LAN their home computers continue to connect with the ISP and the new set top box (video terminal) connects with the video service provider.
Normally, high speed Internet services are delivered to computers, and video services are delivered to set top boxes or Personal Video Recorders. Each service provider normally allocates its own IP address, subnet mask, default gateway and DNS so that the subscriber can connect the right equipment with the right service provider's service. When the subscriber requires two or more service providers, this normally means that there must be two separate IP configurations.
Ideally, the subscriber just connects the new set top box onto their home LAN because the cable is already there and the DSL modem (for example) is already there. But now, the computer and set top box need to receive their IP configuration so that they can communicate with the correct service provider.
One approach is to statically configure routes, subnets and default gateways into the DSL modem, or the set top box, or the computer, or a combination of these.
Another approach is to run new LAN cabling through the home so that there are now two independent home LANs: one for the data service and one for the new video service.
A third approach is for the new video service provider to collaborate with the Internet service provider (ISP) to choose a compatible IP address allocation scheme. Almost without exception, the DHCP protocol is used to allocate the configuration (IP address, subnet mask, default gateway, DNS) for the high speed Internet service. The video service would need to map onto this allocation.
Most ISPs use the DHCP protocol to avoid forcing the subscriber to have to manually configure settings in their modem and computer. DHCP fails if there is more than one service provider and more than one DHCP server because DHCP has no built-in concept of multi-service. DHCP can only be used if the video service provider collaborates with the high speed Internet service provider and one of the two service providers takes responsibility for the DHCP service. Most DSL markets have tens or hundreds of different ISPs offering service and so it is complicated for the video service provider to make this many different arrangements. It is also complex if a customer wants to change from one service provider to another.
Alternately, the video service provider could try to explain how to reconfigure the subscriber's equipment to support the video and the data service. This is difficult because there are so many different types of end user equipment and because there are so many different ISPs as described above. In any case, most subscribers do not have the technical skills to confidently reconfigure their IP address parameters. Mistakes are easy to make and can be difficult and expensive for a service provider to debug. Fixing a mistake can often require an expert to visit the subscriber's home which is expensive.
Avoiding the multiple IP configuration problem by installing a second Ethernet network inside the home is an interesting solution but installing a new network can be expensive and sometimes difficult in an old home. Usually, the subscriber would also need to purchase a new DSL modem that can support two independent Ethernet ports because most DSL modems only support one local network. Most subscribers would not prefer the expense of recabling and buying a new modem if they could somehow reuse their existing cable and modem.
Many DSL modems now implement address sharing capabilities so that one public network address is shared between a potentially large number of computer or video devices. If a subscriber connects a set top box or other video device to the home LAN, the address which is configured for that device could be the same address being allocated to other subscribers' devices by their respective modems. In this way, the video terminal does not have a unique IP address with which to communicate with a centralised video server.